x[0]={0.4,0,0}
h=500

figure(1);

plot(a(:,1),a(:,2));grid on;
xlabel('time/s');
ylabel('Response'); 
legend('歐拉法');
title('步距h=0.0001');


figure(2);

plot(b(:,1),b(:,2));grid on;
xlabel('time/s');
ylabel('Response'); 
legend('二階龍格庫塔');
title('步距h=0.005');

figure(3)

plot(c(:,1),c(:,2));grid on;
xlabel('time/s');
ylabel('Response'); 
legend('四階龍格庫塔');
title('步距h=0.05');



figure(4)
plot(a(:,1),(a(:,2)-1)*100/1,'-r',b(:,1),(b(:,2)-1)*100/1,'.b',c(:,1),(c(:,2)-1)*100/1,'-+g');grid on;
xlabel('time/s');
ylabel('err%'); 
legend('歐拉偏差','二階龍格庫塔偏差','四階龍格庫塔偏差');
title('數(shù)值積分誤差分析圖')；



figure(4)
plot(a(:,1),(a(:,2)-1)*100/1,'-r',b(:,1),(b(:,2)-1)*100/1,'.b');grid on;
xlabel('time/s');
ylabel('err%'); 
legend('二階龍格庫塔偏差','四階龍格庫塔偏差');
title('數(shù)值積分誤差分析圖')；